OFFSET
1,1
COMMENTS
All natural numbers larger than 8 except 10.
Equivalently, numbers n that can be partitioned into three distinct parts a, b, and c, where a + b > c, a + c > b, and b + c > a (or, without loss of generality, into (a, b, c) with a < b < c < a + b). A subsequence of A009005. The unique terms in A107576.
For k > 2, (k-1, k, k+1) gives perimeter 3k and (k-1, k+1, k+2) gives perimeter 3k + 2. For k > 3, the scalene triangle (k-1, k, k+2) has perimeter 3k + 1.
FORMULA
a(n) = n + 9 for n > 1.
EXAMPLE
The integer-sided scalene triangle of least perimeter has sides of lengths 2, 3, and 4, so a(1) = 2 + 3 + 4 = 9.
PROG
(PARI) vector(100, n, if(n==1, 9, n+9)) \\ Altug Alkan, Oct 28 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Rick L. Shepherd, Oct 27 2015
STATUS
approved